What it means
Idle-speed selector input reads stuck high — short to battery voltage or analog signal at maximum. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
The engine idle speed selector switch sends the control module a signal representing the operator's requested idle setting. This circuit-high code sets when the signal stays above its expected range, often because the signal wire is shorted to battery voltage or the supply wire is contacting a battery-positive source.
Common causes
Most likely first.
- Switch wire shorted to battery voltage
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check engine light on
- Idle speed too high, too low, or unstable
- Possible stalling at idle or after cold start
How to diagnose it
- Save freeze-frame data and monitor the selector input live while changing switch positions to confirm it remains at the high end.
- Inspect the selector connector and harness for pinched or chafed insulation, corrosion, loose pins, or contact with a battery-positive wire.
- Use the wiring diagram to test the selector signal wire for an unintended connection to battery voltage.
- Check the selector's supply, ground, and connector contacts against the manufacturer's specification.
- If the external circuit passes, test the switch output and control-module input using the manufacturer's diagnostic procedure.
Common fixes
- Repair a selector signal wire shorted to battery voltage.
- Free a pinched supply wire from the battery-positive source and repair damaged insulation.
- Clean or replace corroded or loose connector terminals.
- Replace the selector switch if it produces a high signal despite a sound circuit.
Can I keep driving?
If the engine idles steadily, short trips may be possible, but the selected idle setting may not be recognized and idle behavior can become unpredictable. Avoid relying on fast idle for equipment and stop if the engine races, stalls, or becomes difficult to control.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.